Standardized cargo containers in the form of load-carrying trailers adapted for securement to chassis of transport tractors or to structural storage members aboard ship are widely in use. Many of these containers require power, e.g. containers incorporating refrigeration apparatus for regulating the temperature of the contents. When the containers are on board ship, power is commonly supplied from the ship's generator to receptacles strategically located in the ship's storage area and connected via cables to the individual containers. Typically, each receptacle has an associated circuit breaker, which can be manually activated to energize and deenergize the receptacle. When the containers are stored on shore, as on a dock, a similar arrangement of receptacles and cables is used, though power is supplied from some other source, e.g. municipal power. These arrangements, however, have several drawbacks.
A significant drawback is that the receptacles and circuit breakers are hard wired in place to such immovable objects as bulkheads aboard ship, steel poles sunk into pavement, concrete buffer walls, etc. Consequently, repair or replacement of a receptacle or circuit breaker must be accomplished on site, which almost invariably is an outdoor location exposed to the elements. Such maintenance can be uncomfortable in unpleasant weather, and can be seriously inhibited as in cold weather, where gloves worn for warmth limit the dexterity required for maintenance operations. Damp, wet conditions add a safety hazard, as the possibility of severe shock is an ever present danger at the power levels involved. As a consequence of the foregoing, the hard wired systems currently in use often go without maintenance during inclement conditions, which can extend over an entire winter season.
Another drawback of the available hard wired arrangements is that the cable plug does not have to be fully inserted in the receptacle to render the arrangement operational. The resulting high resistance at the connection points can result in heat build-up, which can eventually burn out the plug, the receptacle, and the circuit breaker.
Yet another drawback of the hard wired arrangements is that the available locking features for securing the plug to the receptacle are exposed to the elements. Consequently, it is not uncommon for these locking features to become iced over and rendered inoperable.
Yet an additional drawback is that the circuit breakers in the available hard wired arrangements are secured in place by a holding assembly configured to hold only a specific model of circuit breaker. Because circuit breakers are regularly obsoleted by manufacturers, this often results in extensive re-working or replacement of the holding assembly to accommodate a new breaker when an obsoleted breaker fails. This can result in the unit being out of service for an extended period of time, an obviously undesirable consequence. Yet an additional drawback of the hard wired arrangements is that some of the internal components are not corrosion resistant, and hence eventually break down and require replacement.